Casting apparatus



Dec. 1, 1953 R. P. DAVIS CASTING APPARATUS Filed Sept. 6, 1950 INVENTOR.Bav/i I. Dal/61s. BY WM Patented Dec. 1, 1953 CASTING APPARATUS Ralph'1. Davis, Squantum, Mass, assignor "to Walworth Company, Boston, Mass.,a corporation of Massachusetts Application September 6, 1950, Serial No.183,363

Claims. .1

This invention relates to casting apparatus and method and moreparticularly to metal pouring apparatus and method for use withshell-type molds.

Molds of the thin walled shell-type are comprised of a major portion ofan inorganic molding material, such as, sand, and a minor portion of acomponent serving to bind the inorganic material. The completed moldsare in two or more matching parts having the form of hard thin shells ofsubstantial strength. The inner faces ofthe matching parts are smooth.and finished whereas the outer surfaces are left in a rough andirregular condition. Consequently, during the casting operation usingsuch molds the, common weighting methods for ordinary sand molds cannotbe used with any degree of success.

In casting operations using shell-type molds it has been customary toembed the mold parts in a loose, relatively coarse granular materialwith the intention of enabling the mold to withstand the static pressureof the molten metal. Refractory materials such as steel shot, sand andgravel have been proposed as suitable bedding material to be containedin the pouring box. This expedient does not, however, provide uniformpressure on the mold parts and in some cases is considerably less thanthe pressure exerted by the molten metal. The resulting separation ordistortion of the mold parts during the casting operation causessufiicient nonconformity between the pattern and the casting to renderthe latter completely useless. Consequently, the desirable features ofthe shell-type mold have been outweighed by the difliculty of producingsatisfactory castings with such molds.

An object of the present invention is to supsupport shell-type moldsduring the casting operation under substantially uniform pressurethroughout the area thereof and suflicient to prevent separation ordistortion of the mold parts. Another object of the invention is toadjust the pressure on the molds in order to approximate or exceed thestatic pressure of the metal poured into the mold.

Another object of the invention is to remove the supporting materialfrom the pouring box in an expeditious manner after the castingoperation.

The apparatus and method for accomplishing these and other objects andadvantages of the invention comprises a pouring box of sufficientdimensions to contain a complete mold in a vertical pouring position.The box is lined on opposite sides with a flexible material, such as arubber diaphragm, providing a space between the liner and the adjacentwall into which fluid under pressure may be admitted. Thus, thediaphragm becomes distended toward the mold from eachside and contactsthe approximate area thereof with a uniform pressure which may be asgreat or greater than the static pressure of the casting material to bepoured into the mold.

In order to protect the diaphragm from the heat of the mold anintermediate material may be used such as steel shot, sand or gravel.This material is poured into the space between the mold and thediaphragm with the mold located approximately midway between theopposite sides of the pouring box. The fluid pressure on the diaphragmsis thus transmitted through the m termediate material to the moldswithout losing any advantages of this invention.

The intermediate material may be easily removed from the box after thecasting operation by the use of fluid pressure or suction applied to thebottom of the box at the appropriate time. The box may be speciallyformed to facilitate the shot withdrawal even when the box is completelyfull.

In the accompanying drawings:

Fig. 1 is a plan view of the metal pouring ap paratus showing a mold inposition therein;

Fig. 2 is a cross-section taken on the line II-II '2 Of Fig. 1;

Fig. 3 is a longitudinal section taken on the line III-III of Fig. 2,and

Fig. 4 is an enlarged sectional view taken on the line IV-I'V of Fig. l.

Referring more particularly to the drawing, the pouring box 9 comprisesa generally rectangular casing Ill having an open end [2 and a centrallydisposed, hollow-partition 14. The partition it serves toudivide thevcasing i=8 longitudinally into two halves, each of which. is adapted tocontain a mold. As indicated in Fig. 1 by a broken line 16 a shell-type.mold comprised of two matching parts is positioned in one of the halvesof the pouring box. It will be apparent that a similar or diiferent moldcould be positioned in the other half of the casing it. Moreover, whilea double pouring box is shown and described herein, a single box couldbe used if desired. The length and width of the casing in as viewed inFig; 3 are greater than those of the mold it which is inserted freely inan edgewise direction through the open end I 2. It will be observed thatthe depth of the casing ill on each side of the .parti tion 14, asviewed in Fig. I, and defined by the. opposite side walls of the casing[l0 and partistain is sufficient to space these walls from the molds It.An aperture i9 is provided preferably at one end in each of the sidewalls of the casmg l0 and the partition I4- respectively-for a purposeapparent hereinafter.

Each half of the pouring box- 9 contains a pair of liners :20 ofgenerally rectangular form which are secured at their'marginal edges tothe adjacent side walls. of the-casing I0 and partition [4 respectively.The securing means for the liners may take the form of rivets 22,although bolts or other securing means may equally well be used. Theliners 24 are preferably made of flexible sheet material, such asrubber, although any other resilient or elastic material may beemployed. the liners 20 and the adjacent walls of the casing I0 andpartition I4 is an annular spacer or gasket 25 of rubber or similarresilient material. A retaining ring 28, preferably of metal or otherhard material, is superimposed on each of the liners 22 to provide afirm surface for the rivets 212. In this manner, the liners 22 arespaced from the adjacent walls of the casing I0 and partition M toprovide four chambers 24 which are sealed around the edges by thefastening means described to close the chambers 24 thus provided. Aplurality, in this instance four angle bars extend transversely acrosseach half of the pouring box 9 opposite the open end I2 and may each besecured at one end to the side walls of the casing I6 and at theopposite end to the partition I4 by welding or other suitable means. Asshown more clearly in Fig. 3 each'of the angle bars has the open portionof the angle facing away from the open end I2 of the pouring box 9, thuspresenting a pair of inclined surfaces toward the open end I2. As willbe apparent, the mold I6 may be positioned on the angle bars #30 inpouring position and supported thereby during subsequent operations.

Closure means 32 in the form of an elongated, funnel-shaped member isprovided for the end of the casing opposite the open end I2. The closuremeans 32 conforms to the side and end walls of the casing I0 and may beintegral with these walls as shown or may be formed as a separate partsecured thereto if desired. The closure means 32 has an outlet 34 in theform of a slot extending longitudinally of the neck of thisfunnel-shaped member. An exhaust pipe 36 extends longitudinally of theclosure means 32 and is provided with an elongated recess 38 for thereception of the outlet 34. Preferably, the walls of the recess 38 arewelded or otherwise secured to the side walls of the closure member 32with the outlet 34 positioned substantially coincident with the axis ofthe pipe 36 for a purpose apparent hereinafter.

Means for admitting fluid under pressure to the chambers 24 are providedand take the form of a plurality, in this instance four, elbows 40 onepair being secured as by welding to the exterior side walls of thecasing III on opposite sides thereof and the other pair located withinthe hollow partition I4 for communication with the apertures I9 in theside walls. The elbows 40 connect with suitable piping 42 whichcommunicates with a source of fluid pressure (not shown), such ascompressed air, through a multi- Way valve 44 having an inlet 46 and anexhaust 48 associated therewith. In order that the pressure admitted tothe chambers 24 may be set to a desired value, a suitable pressureregulator 50 may be included in the inlet 46 for this purpose. It willbe understood that separate valves 44 can be provided to control theflow of fluid in the piping 42 to each half of the pouring box 9- or asingle valve 44 may control the flow to both halves.

In order to protect the flexible liners 20 from the heat of the moltenmetal transmitted through the mold l6, an intermediate material is usedbetween the liners 20 and the mold I6. This material is of a granularnature such as Interposed between each of steel shot, sand or gravel andis pourable through the open end I2 after the mold I6 is positioned inthe casing I0. As shown in Fig. 1, the mold I6 is located approximatelymidway between the liners 20 in one-half of the pouring box 9 and thegranular material, indicated by the reference numeral 52, completelyfills the surrounding space. It will be apparent that the closure means32 will also become filled with the granular material 52 and will flowfrom the outlet 34 into the pipe 36. However, since the outlet 34 ispositioned substantially coincident with the axis of the pipe 36 thenthe latter will not be completely blocked by'the granular material evenwhen the casing I0 is completely filled. In some cases it may beadvantageous to insert a rigid plate of metal or other suitable materialbetween the flexible liners 2D and the granular material 52 dependingupon the type of mold I6 which is to be poured. Moreover, water or otherliquid or gas may be used to fill the chamber 24 if desired.

The casing I0 is provided with a plurality, in this instance four,locating lugs 54 one at each corner and suitably perforated to receiveretaining bolts or the like (not shown) by means of which the casing maybe secured to a foundation, as indicated by the broken line 56 in Figs.2 and 3. When so positioned, the closure means 32 and the pipe 36 may becontained in a pit or other depression 58 in the foundation 56 below thesecuring means for the pouring box 9.

OPERATION In the operation of the apparatus, the mold I6 may be insertededgewise into one of the spaces in the casing II! between the side walland the partition i 4. As previously noted, the bottom edge of the moldrests on the angle bars 30 and is positioned approximately midwaybetween the partition I4 and the side wall of the casing I0 and spacedfrom the end walls thereof. While so positioned, the space around themold I6 is filled with the intermediate material such as steel shot,which will serve to support the mold I6 in the desired location.Thereafter, fluid under pressure is admitted by operation of the valve44 to the chambers 24 on each side of the mold I6 thereby compressingthe mold I6 sufficiently to withstand the static pressure of castingmetal which can then be poured in molten condition into the mold I6 inthe usual manner. The pressure of the fluid can be set to approximate orbe greater than the static pressure of the metal poured into the mold I6so that no separation or distortion of the mold parts can occur.

Upon termination of the pouring operation and cooling of the castingmetal, the valve 44 is operated to exhaust the pressure fluid in thecham-- bers 24. The steel shot can then be expeditiously removed byapplication of suction to the pipe 36 which will carry the shot to acommon sump (not shown). The arrangement of the outlet 34 within thepipe 36, as previously described, makes it possible for the suctionfluid to reach high velocity even when the casing I I! is filled withthe refractory material, since the pipe 36 itself cannot becomecompletely filled or blocked.

It will be apparent that casting apparatus for use in pouring moldshaving an irregular exterior surface has been provided and that the de-"sirable features of shell-type molds are preserved durlng the castingoperation. It will furtherbe apparent that many changes may be made inthe details of construction and arrangement of parts and in the steps ofthe method without" departing from the scope of the invention as definedin the appended claims.

I claim:

1. Casting apparatus for a shell-type mold. comprising a casing havingan area adapted to contain the mold, said casing having a depth definedby opposite sid walls adapted to be spaced from the mold, a pair offlexible liners extending across said opposite walls andformingtherewith a pair of closed chambers within said casing, granularmaterial contained between said spaced mold and opposite side walls, andmeans for admitting fluid under pressure to said chambers to distendsaid liners relative to said opposite walls, said liners being therebycooperable with said granular material and adapted to compress the moldsufliciently to withstand the static pressure of casting material duringthe casting operation.

2. Casting apparatus as defined in claim 1 wherein said casing isgenerally rectangular having an open end, said liners being of generallyrectangular form secured at the marginal edges to the adjacent sideWalls, said side walls having apertures therein with which said meansfor admitting fluid communicate.

3. Casting apparatus for a shell-type mold, comprising a casing havingan area adapted to contain the mold, said casing having a depth definedby opposite side walls adapted to be spaced from the mold, a pair offlexible liners extending across said opposite walls and forming therewith a pair of closed chambers Within the casing, granular materialcontained between said spaced mold and opposite side walls, closuremeans for one end of said casing having an outlet therein for saidgranular material, means for admitting fluid under pressure to saidchambers to distend said liners relative to said opposite sid walls,said liners being thereby cooperable with said granular material andadapted to compress the mold sufficiently to withstand the staticpressure of casting material during the casting operation, and meansoperable for withdrawing said granular material from said outlet upontermination of said casting operation.

4. Casting apparatus as defined in claim 3 wherein said withdrawingmeans comprises a suction pipe communicating with said aperture.

5. Casting apparatus as claimed in claim 4 wherein said closure meansare connected to said pip with said outlet substantially coincident withthe axis of said pipe to prevent blocking thereof by said material.

6. Casting apparatus for a shell-type mold, comprising a generallyrectangular casing having an open end and a length and width adapted tocontain the mold inserted through said open end, said casing having adepth defined by opposite side walls adapted to be spaced from the mold,a pair of flexible liners of generally rectangular form secured at themarginal edges to the adjacent side walls and forming therewith a pairof closed chambers within said casing, granular material containedbetween said spaced mold and opposite side walls, said material beingrefractory and pourable through said open end, closure means for theopposite end of said casing having an elongated outlet therein for saidgranular material, means for admitting fluid under pressure to saidchambers to distend said liner away from said opposite sid walls, saidliners being thereby cooperable with said granular material and adaptedto compress the mold sufficiently to withstand the static pressure ofcasting material during the casting operation, and a suction pipeextending substantially parallel with said closure means and having anelongated recess for receiving said outlet substantially coincident withthe axis of said pip to prevent blocking thereof by said material.

7. Casting apparatus for shell-type molds, comprising a generallyrectangular casing having an open end and a centrally disposedpartition, said casing having a length and width adapted to contain amold on each side of the partition inserted through said open end, saidcasing having a depth defined by opposite side walls of said casing andpartition adapted to be spaced from the molds, a pair of flexible linersof generally rectangular form secured at the marginal edges to theadjacent side walls of said casing and partition respectively andforming therewith a pair of chambers on each side of said partitionwithin said casing, granular material contained between said spacedmolds and opposite side walls, said material being refractory andpourable through said open end, a funnel-shaped closure means for theopposite end of said casing having an elongated outlet therein for saidgranular material, means for admitting fluid under pressure to saidchambers to distend said liners away from said opposite side walls, saidliners being thereby cooperable with said granular material and adaptedto compress the molds sufficiently to withstand the static pressure ofcasting material during the casting operation, and a suction pipeextending substantially parallel with said closure means and having anelongated recess for receiving said outlet substantially coincident withthe axis of said pipe to prevent blocking thereof by said material.

8. A method of casting with shell-type molds comprising inserting a moldsubstantially midway between spaced oppositely disposed flexiblesurfaces, positioning granular refractory material in said spacesbetween the mold and said surfaces, and applying fluid under pressure tosaid surfaces to distend the same and compress the granular materialtoward said mold for supporting said mold during the casting operationunder substantially uniform pressure at least equal to the staticpressure of the casting material.

9. The method as claimed in claim 8 wherein said granular material ispoured in said spaces between the mold and said flexible surfaces tocompletely fill the same.

10. The method as claimed in claim 9 wherein said fluid pressure isreleased following said casting operation and thereafter said granularmaterial is withdrawn by suction from said spaces.

RALPH P. DAVIS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 353,832 Tasker Dec. 7, 1886 1,653,232 Smith Dec. 20, 19272,088,123 Toman July 27, 1937 2,192,133 Hagemeyer Feb. 27, 19402,383,224 Sorensen Aug. 21, 1945 OTHER REFERENCES Page 506, MetalIndustry, December 19, 1947.

